Needs and Targets for the multi sex combs Gene Product in Drosophila melanogaster

Abstract We have analyzed the requirements for the multi sex combs (mxc) gene during development to gain further insight into the mechanisms and developmental processes that depend on the important trans-regulators forming the Polycomb group (PcG) in Drosophila melanogaster. mxc is allelic with the tumor suppressor locus lethal (1) malignant blood neoplasm (l(1)mbn). We show that the mxc product is dramatically needed in most tissues because its loss leads to cell death after a few divisions. mxc has also a strong maternal effect. We find that hypomorphic mxc mutations enhance other PcG gene mutant phenotypes and cause ectopic expression of homeotic genes, confirming that PcG products are cooperatively involved in repression of selector genes outside their normal expression domains. We also demonstrate that the mxc product is needed for imaginal head specification, through regulation of the ANT-C gene Deformed. Our analysis reveals that mxc is involved in the maternal control of early zygotic gap gene expression previously reported for some PcG genes and suggests that the mechanism of this early PcG function could be different from the PcG-mediated regulation of homeotic selector genes later in development. We discuss these data in view of the numerous functions of PcG genes during development.

Download Full-text

Genetic analysis of the additional sex combs locus of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/130.4.817 ◽

1992 ◽

Vol 130 (4) ◽

pp. 817-825 ◽

Cited By ~ 1

Author(s):

D A Sinclair ◽

R B Campbell ◽

F Nicholls ◽

E Slade ◽

H W Brock

Keyword(s):

Drosophila Melanogaster ◽

Chromatin Structure ◽

Polycomb Group ◽

Homeotic Genes ◽

Sex Combs ◽

Normal Expression ◽

Additional Sex Combs ◽

Unusual Phenotype ◽

New Alleles

Abstract Additional sex combs (Asx) is a member of the Polycomb group of genes, which are thought to be required for maintenance of chromatin structure. To better understand the function of Asx, we have isolated nine new alleles, each of which acts like a gain of function mutation. Asx is required for normal determination of segment identity. AsxP1 shows an unusual phenotype in that anterior and posterior homeotic transformations are seen in the same individuals, suggesting that AsxP1 might upset chromatin structure in a way that makes both activation and repression of homeotic genes more difficult. Analysis of embryonic and adult phenotypes of Asx alleles suggests that Asx is required zygotically for determination of segment number and polarity. The expression pattern of even-skipped is altered in Asx mutant embryos, suggesting that Asx is required for normal expression of this gene. We have transposon-tagged the Asx gene, and can thus begin molecular analysis of its function.

Download Full-text

Maintenance of the engrailed expression pattern by Polycomb group genes in Drosophila

Development ◽

10.1242/dev.116.3.805 ◽

1992 ◽

Vol 116 (3) ◽

pp. 805-810 ◽

Cited By ~ 7

Author(s):

D. Moazed ◽

P.H. O'Farrell

Keyword(s):

Expression Pattern ◽

Expression Patterns ◽

Ectopic Expression ◽

Polycomb Group ◽

Homeotic Genes ◽

Polycomb Group Genes ◽

Sex Combs ◽

Segment Polarity ◽

Selector Genes ◽

Stable Maintenance

The stable maintenance of expression patterns of homeotic genes depends on the function of a number of negative trans-regulators, termed the Polycomb (Pc) group of genes. We have examined the pattern of expression of the Drosophila segment polarity gene, engrailed (en), in embryos mutant for several different members of the Pc group. Here we report that embryos mutant for two or more Pc group genes show strong ectopic en expression, while only weak derepression of en occurs in embryos mutant for a single Pc group gene. This derepression is independent of two known activators of en expression: en itself and wingless. Additionally, in contrast to the strong ectopic expression of homeotic genes observed in extra sex combs- (esc-) mutant embryos, the en expression pattern is nearly normal in esc- embryos. This suggests that the esc gene product functions in a pathway independent of the other genes in the group. The data indicate that the same group of genes is required for stable restriction of en expression to a striped pattern and for the restriction of expression of homeotic genes along the anterior-posterior axis, and support a global role for the Pc group genes in stable repression of activity of developmental selector genes.

Download Full-text

Ten different Polycomb group genes are required for spatial control of the abdA and AbdB homeotic products

Development ◽

10.1242/dev.114.2.493 ◽

1992 ◽

Vol 114 (2) ◽

pp. 493-505 ◽

Cited By ~ 28

Author(s):

J. Simon ◽

A. Chiang ◽

W. Bender

Keyword(s):

Expression Patterns ◽

Ectopic Expression ◽

Specific Pattern ◽

Polycomb Group ◽

Polycomb Group Genes ◽

Sex Combs ◽

Normal Expression ◽

Sex Comb ◽

Regulatory Dna ◽

Pair Rule

Mutations in genes of the Polycomb (Pc) group cause abnormal segmental development due to ectopic expression of the homeotic products of the Antennapedia and bithorax complexes. Here the requirements for Pc group genes in controlling the abdA and AbdB products of the bithorax complex are described. Embryos containing mutations in the genes Polycomb (Pc), extra sex combs (esc), Enhancer of zeste [E(z)], polyhomeotic (ph), Sex comb on midleg (Scm), Polycomb-like (Pcl), Sex comb extra (Sce), Additional sex combs (Asx), Posterior sex combs (Psc) and pleiohomeotic (pho) were examined. In every case, both abdA and AbdB are expressed outside of their normal domains along the anterior-posterior (A-P) axis, consistent with these Pc group products acting in a single pathway or molecular complex. The earliest detectable ectopic expression is highest in the parasegments immediately adjacent to the normal expression boundary. Surprisingly, in the most severe Pc group mutants, the earliest ectopic AbdB is distributed in a pair-rule pattern. At all stages, ectopic abdA in the epidermis is highest along the anterior edges of the parasegments, in a pattern that mimics the normal abdA cell-specific pattern. These examples of highly patterned mis-expression show that Pc group mutations do not cause indiscriminate activation of homeotic products. We suggest that the ectopic expression patterns result from factors that normally activate abdA and AbdB only in certain parasegments, but that in Pc group mutants these factors gain access to regulatory DNA in all parasegments.

Download Full-text

DSP1, an HMG-like Protein, Is Involved in the Regulation of Homeotic Genes

Genetics ◽

10.1093/genetics/157.1.237 ◽

2001 ◽

Vol 157 (1) ◽

pp. 237-244

Author(s):

M Decoville ◽

E Giacomello ◽

M Leng ◽

D Locker

Keyword(s):

Null Allele ◽

Genetic Interaction ◽

Polycomb Group ◽

Homeotic Genes ◽

Loss Of Function ◽

Sex Combs Reduced ◽

Trithorax Group ◽

Sex Combs ◽

Normal Expression ◽

Sex Comb

Abstract The Drosophila dsp1 gene, which encodes an HMG-like protein, was originally identified in a screen for corepressors of Dorsal. Here we report that loss of dsp1 function causes homeotic transformations resembling those associated with loss of function in the homeotic genes Sex combs reduced (Scr), Ultrabithorax (Ubx), and Abdominal-B. The expression pattern of Scr is altered in dsp1 mutant imaginal discs, indicating that dsp1 is required for normal expression of this gene. Genetic interaction studies reveal that a null allele of dsp1 enhances trithorax-group gene (trx-G) mutations and partially suppresses Polycomb-group gene (Pc-G) mutations. On the contrary, overexpression of dsp1 induces an enhancement of the transformation of wings into halteres and of the extra sex comb phenotype of Pc. In addition, dsp1 male mutants exhibit a mild transformation of A4 into A5. Comparison of the chromatin structure at the Mcp locus in wild-type and dsp1 mutant embryos reveals that the 300-bp DNase I hypersensitive region is absent in a dsp1 mutant context. We propose that DSP1 protein is a chromatin remodeling factor, acting as a trx-G or a Pc-G protein depending on the considered function.

Download Full-text

Ectopic expression of homeotic genes caused by the elimination of the Polycomb gene in Drosophila imaginal epidermis

Development ◽

10.1242/dev.104.4.713 ◽

1988 ◽

Vol 104 (4) ◽

pp. 713-720 ◽

Cited By ~ 19

Author(s):

A. Busturia ◽

G. Morata

Keyword(s):

Ectopic Expression ◽

Homeotic Genes ◽

Sex Combs Reduced ◽

Hierarchical Order ◽

Sex Combs ◽

Morphological Patterns

The morphological patterns in the adult cuticle of Drosophila are determined principally by the homeotic genes of the bithorax and Antennapedia complexes. We find that many of these genes become indiscriminately active in the adult epidermis when the Pc gene is eliminated. By using the Pc3 mutation and various BX-C mutant combinations, we have generated clones of imaginal cells possessing different combinations of active homeotic genes. We find that, in the absence of BX-C genes, Pc- clones develop prothoracic patterns; this is probably due to the activity of Sex combs reduced which overrules Antennapedia. Adding contributions of Ultrabithorax, abdominal-A and Abdominal-B results in thoracic or abdominal patterns. We have established a hierarchical order among these genes: Antp less than Scr less than Ubx less than abd-A less than Abd-B. In addition, we show that the engrailed gene is ectopically active in Pc- imaginal cells.

Download Full-text

Comparison of germline mosaics of genes in the Polycomb group of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/140.1.231 ◽

1995 ◽

Vol 140 (1) ◽

pp. 231-243 ◽

Cited By ~ 5

Author(s):

M C Soto ◽

T B Chou ◽

W Bender

Keyword(s):

Drosophila Melanogaster ◽

Target Genes ◽

Cell Types ◽

Mitotic Recombination ◽

Polycomb Group ◽

Specific Cell ◽

Independent Functions ◽

Sex Combs ◽

Null Phenotype ◽

Additional Sex Combs

Abstract The genes of the Polycomb group (PcG) repress the genes of the bithorax and Antennapedia complexes, among others. To observe a null phenotype for a PcG gene, one must remove its maternal as well as zygotic contribution to the embryo. Five members of the PcG group are compared here: Enhancer of Polycomb [E(Pc)], Additional sex combs (Asx), Posterior sex combs (Psc), Suppressor of zeste 2 [Su (z) 2] and Polycomblike (Pcl). The yeast recombinase (FLP) system was used to induce mitotic recombination in the maternal germline. Mutant embryos were analyzed by staining with antibodies against six target genes of the PcG. The loss of the maternal component leads to enhanced homeotic phenotypes and to unique patterns of misexpression. E(Pc) and Su(z) 2 mutations had only subtle effects on the target genes, even when the maternal contributions were removed. Asx and Pcl mutants show derepression of the targets only in specific cell types. Psc shows unusual effects on two of the targets, Ultrabithorax and abdominal-A. These results show that the PcG genes do not act only in a common complex or pathway; they must have some independent functions.

Download Full-text

A genetic and molecular analysis of an invectedDominant mutation in Drosophila melanogaster

Genome ◽

10.1139/g98-026 ◽

1998 ◽

Vol 41 (3) ◽

pp. 381-390 ◽

Cited By ~ 1

Author(s):

A J Simmonds ◽

J B Bell

Keyword(s):

Drosophila Melanogaster ◽

Imaginal Disc ◽

Transcriptional Start Site ◽

Ectopic Expression ◽

Careful Analysis ◽

Wing Imaginal Disc ◽

Coding Region ◽

Specific Expression ◽

Additional Lesion ◽

Normal Expression

The invected gene of Drosophila melanogaster is a homeobox-containing gene that is closely related to engrailed. A dominant gain of function allele, invectedDominant, was derived from mutagenesis of a dominant allele of vestigial, In(2R)vgW. A careful analysis of the phenotype of invectedDominant shows that it is associated with a transformation of the anterior compartment of the wing to a posterior fate. This transformation is normally limited to the wing blade itself and does not involve the remaining tissues derived from the wing imaginal disc, including the wing hinge and dorsal thorax of the fly. The ectopic expression of invected protein associated with invectedDominant correlates spatially with the normal expression pattern of vestigial in the wing imaginal disc, suggesting that control elements of vestigial are driving ectopic invected expression. This was confirmed by sequence analysis that shows that the dominant vestigial activity was eliminated by a deletion that removes the 3' portion of the vestigial coding region. This leaves a gene fusion wherein the vestigial enhancer elements are still juxtaposed immediately 5' to the invected transcriptional start site, but with the vg sequences harboring an additional lesion. Unlike recessive invected alleles, the invectedDominant allele produces an observable phenotype, and as such, should prove useful in determining the role of invected in patterning the wing imaginal disc. Genetic analysis has shown that mutations of polyhomeotic, a gene involved in regulating engrailed expression, cause a reproducible alteration in the invectedDominant phenotype. Finally, the invectedDominant allele should prove valuable for identifying and characterizing genes that are activated within the posterior compartment. A screen using various lacZ lines that are asymmetrically expressed in an anterior-posterior manner in the wing imaginal disc isolated one line that shows posterior-specific expression within the transformed anterior compartment.Key words: Drosophila, development, dominant mutation, ectopic, wings.

Download Full-text

Molecular characterisation of the Polycomblike gene of Drosophila melanogaster, a trans-acting negative regulator of homeotic gene expression

Development ◽

10.1242/dev.120.9.2629 ◽

1994 ◽

Vol 120 (9) ◽

pp. 2629-2636 ◽

Cited By ~ 19

Author(s):

A. Lonie ◽

R. D'Andrea ◽

R. Paro ◽

R. Saint

Keyword(s):

Gene Expression ◽

Drosophila Melanogaster ◽

Polycomb Group ◽

Negative Regulator ◽

Homeotic Gene ◽

Homeotic Genes ◽

Molecular Characterisation ◽

Polycomb Group Proteins ◽

Polycomb Group Genes ◽

Homeotic Gene Expression

The Polycomblike gene of Drosophila melanogaster, a member of the Polycomb Group of genes, is required for the correct spatial expression of the homeotic genes of the Antennapaedia and Bithorax Complexes. Mutations in Polycomb Group genes result in ectopic homeotic gene expression, indicating that Polycomb Group proteins maintain the transcriptional repression of specific homeotic genes in specific tissues during development. We report here the isolation and molecular characterisation of the Polycomblike gene. The Polycomblike transcript encodes an 857 amino acid protein with no significant homology to other proteins. Antibodies raised against the product of this open reading frame were used to show that the Polycomblike protein is found in all nuclei during embryonic development. Antibody staining also revealed that the Polycomblike protein is found on larval salivary gland polytene chromosomes at about 100 specific loci, the same loci to which the Polycomb and polyhomeotic proteins, two other Polycomb Group proteins, are found. These data add further support for a model in which Polycomb Group proteins form multimeric protein complexes at specific chromosomal loci to repress transcription at those loci.

Download Full-text

H3K27 modifications define segmental regulatory domains in the Drosophila bithorax complex

eLife ◽

10.7554/elife.02833 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 69

Author(s):

Sarah K Bowman ◽

Aimee M Deaton ◽

Heber Domingues ◽

Peggy I Wang ◽

Ruslan I Sadreyev ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Binding Protein ◽

Histone H3 ◽

Polycomb Group ◽

Homeotic Genes ◽

Bithorax Complex ◽

Body Segment ◽

Regulatory Domains ◽

Definition Of ◽

Identity Expression

The bithorax complex (BX-C) in Drosophila melanogaster is a cluster of homeotic genes that determine body segment identity. Expression of these genes is governed by cis-regulatory domains, one for each parasegment. Stable repression of these domains depends on Polycomb Group (PcG) functions, which include trimethylation of lysine 27 of histone H3 (H3K27me3). To search for parasegment-specific signatures that reflect PcG function, chromatin from single parasegments was isolated and profiled. The H3K27me3 profiles across the BX-C in successive parasegments showed a ‘stairstep’ pattern that revealed sharp boundaries of the BX-C regulatory domains. Acetylated H3K27 was broadly enriched across active domains, in a pattern complementary to H3K27me3. The CCCTC-binding protein (CTCF) bound the borders between H3K27 modification domains; it was retained even in parasegments where adjacent domains lack H3K27me3. These findings provide a molecular definition of the homeotic domains, and implicate precisely positioned H3K27 modifications as a central determinant of segment identity.

Download Full-text

Genetic analysis of the enhancer of zeste locus and its role in gene regulation in Drosophila melanogaster.

Genetics ◽

10.1093/genetics/126.1.185 ◽

1990 ◽

Vol 126 (1) ◽

pp. 185-199 ◽

Cited By ~ 9

Author(s):

R S Jones ◽

W M Gelbart

Keyword(s):

Gene Regulation ◽

Drosophila Melanogaster ◽

Ectopic Expression ◽

Polycomb Group ◽

Temperature Sensitive ◽

Loss Of Function ◽

Eye Color ◽

Polycomb Group Genes ◽

Enhancer Of Zeste ◽

Gene Complexes

Abstract The Enhancer of zeste [E(z)] locus of Drosophila melanogaster is implicated in multiple examples of gene regulation during development. First identified as dominant gain-of-function modifiers of the zeste1-white (z-w) interaction, mutant E(z) alleles also produce homeotic transformations. Reduction of E(z)+ activity leads to both suppression of the z-w interaction and ectopic expression of segment identity genes of the Antennapedia and bithorax gene complexes. This latter effect defines E(z) as a member of the Polycomb-group of genes. Analysis of E(z)S2, a temperature-sensitive E(z) allele, reveals that both maternally and zygotically produced E(z)+ activity is required to correctly regulate the segment identity genes during embryonic and imaginal development. As has been shown for other Polycomb-group genes, E(z)+ is required not to initiate the pattern of these genes, but rather to maintain their repressed state. We propose that the E(z) loss-of-function eye color and homeotic phenotypes may both be due to gene derepression, and that the E(z)+ product may be a general repressing factor required for both examples of negative gene regulation.

Download Full-text